This invention relates to a method and apparatus for laboratory handling of liquid samples such as body fluids containing particulate components. In more detail, the present invention provides a convenient and inexpensive system for extracting a separated fluid phase from the sample and also provides means for coordinating the extracted phase with the remainder of the sample.
In the field of clinical testing, the analysis of liquid samples such as body fluids containing particulate components, is commonly performed to quantitatively and qualitatively determine the constituents present. The results of such analysis provides a valuable diagnostic tool which aids in the determination of pathological conditions in the body and in detection of various diseases.
The procedures carried out in analysis of a body fluid, such as a blood sample, are well known and do not form part of the present invention. However, there are numerous problems encountered by laboratory technicians in connection with the handling of these samples. Typically, a blood sample obtained from a patient is drawn into a test tube which is thereafter capped and sent to a laboratory for testing. In the laboratory, the test tube containing the blood sample is centrifuged to separate particulate matter, such as blood cells, from fluid phase, such as serum or plasma. After centrifuging, the fluid phase of the sample normally floats as a distinct upper layer separate from the particulate components which are concentrated in the lower portion of the test tube.
Many prior attempts have been made to prevent recombining of separated phases in a processed sample. When successful, several analyses of the separated fluid phase can be performed over prolonged periods of time without the need for extracting additional samples from the patient. One such attempt, disclosed in U.S. Pat. No. 3,780,935, has suggested the use of a physical barrier or sealant between the separated phases of the sample.
Another prior attempt to maintain the integrity of separated sample phases has suggested that the extracted fluid phase be isolated in a separate vial. However, due to a very large number of different samples being analyzed by a laboratory, there is an increased likelihood that isolated vials will become disassociated from the remainder of the original sample. Should this occur, and if additional fluid phase analyses are required, it may be necessary to extract additional samples from the patient and in effect, start the analysis over again.
A further problem related to laboratory handling of liquid samples, such as body fluids, is that of contamination. Quite frequently, in connection with communicable diseases, the inside portion of the sample container will be contaminated, particularly in the area where a cap has been used to cover the container during shipment to the laboratory. Consequently, technicians are exposed to a direct threat of contamination by handling the container and an indirect threat by handling equipment, such as pipettes, used to transfer the sample.
The present invention overcomes the foregoing deficiences of the prior devices related to liquid sample analysis and provides an improved method and apparatus for sample handling which achieves an accurate analysis with diminished likelihood of contamination.